High frequency wave translating device



March 1959 D. J. SOMMERS arm, 2,877,429

HIGH FREQUENCY WAVE TRANSLATING DEVICE Filed Oct. 6, 1955 Donald J. Sommers INVENTOR.

2? V Fig. William J. Wilson United statesPfltn HIGH FREQUENCY WEAYEITRANSLATING DEVICE -lionald J. Sommers, Brookline, ii 'd williain 1 W Nashua, N. H., assignors, by niesne assignments, to Sanders Associates, Inc., Nashua, N; H; a corporation of Delaware Application October 6, S e'fial'N'o. 553 3386 Claims. (Cl. 333- 24) The invention relates to freq uency wave translating device s for propagatinghigh frequency energy from one transmission line to another or from atransmission line to space. More particularly, the inven'tion relates tohigh frequencytransmission lines and antennas.

, Inthe prior art it is common practice to utilize a slot radiator in such wave guide transmission Iinesfo'r radiating energy into space or translating energy from one type of wave guide to another. In flat-strip transmission lines utilizing an elongated, inner conductor disposed in parallel with and in insulated spaced relation between two outer conductors, resonant slots formedin one of the outer conductors have been found to, provide inadequate radiation for practical purposes. or One type of fiat-strip transmission line is commonly ,-termed sandwich line and this line will be the one considered hereinafter.

. It is therefore an object of the invention to provide an improved high frequency waveQtran slatin'g device.

A further object of the invention is to provide animproved high frequency wave translating device providing increased radiation efiiciency i o A further objectof the invention is to provide an improved high frequency slot'antenna coupled to sandwich line.

Still another object of the invention is to provide an improved coupling device between sandwich line and wave guide line. o, t: J

In accordance with theinvention there isprovide'd a high frequency wavetranslating devicle comprising a pair of elongated, outer conductors providing ground planes.

An elongated, inner conductor is disposed inparallel with and in insulated spaced relation between the outer conductors. A resonant, elongatedsllot is; formed .transversely in one of the outer eonductors. The slot overlays 'pointed out in the appended claims.

Referring now to the drawings:

Fig. 1 is an exploded view of a preferred embodiment of the invention;

Fig. 2 is a plan view, partly in section, of the embodiment in Fig. l; I

Fig. 3 is a sectional view of the preferred embodiment taken along the lines 33 of Fig. 2; and

Fig. 4 is a plan view of a modification of the embodiment in Fig. 1.

Detailed description Referring now more particularly to Figs. 1, 2 and 3,

, 2,877,429 Fatented Mar. 10,

there is represented a high frequency wave translating device comprising a pair of elongated, outer conductors nect the outer conductors 10 19 and 11 providing ground planes. Elongated, inner conductors 12 and 13 in direct contact with each other and electrically functioning as a single conductor are disposed in parallel with and fixedin insulated spaeed relation between the outer conductors by dielectric members 15 and 16. A resonant, elongated slot '14 is formed in the outer conductor 10 intersecting an axis parallel with the inner conductor 12 as shown. The inner conductors 12 and 13 have tapered portions 23 as shown for matching the impedance of the sandwich transmission line to the slot. Aplurality of conductive rods 17 conand 11 through the dielectric members 15 and 16 adjacent the opposite sides ofthe slot 14. One of the rods 11 is disposed in the vicinity of each corne-r of the outer conductor as defined by the intersection of the-innerconductor and the slot. -A wave guide transmission line 18 is connected to the outer conductor 10 with a propagation boundary adjacent each extremity of the slot 14 as shown in Fig. 2. The guide 18 is mounted on the outer conductor 10 with, for example,

screws 19 which are inserted through screw holes 21 in a flange 22 of the guide 18 into holes 20 in the sandwich transmission line. o o

r The embodiment shown in Fig. 4 differs from that represented by Figs. 13, inclusive, in that in Fig. 4 a conductor tab 24 extends from theouter conductor 11) into the slot 14 for tuning the slot and matching its impedance to that of the transmission line.

Operation Co nsidering now the operation of the wave translating device just described and referring to Figs. 1, 2 and 3,

energy is propagated along the sandwich transmission line toward the slot '14 in the wellknown TEM mode.

The outer conductors 1'0 and 11 provide boundary ground vicinity of the intersection between the s'lot14 and the inner conductors 12 and #13 substantially increasest'he radiation efiiciency of the slot 14. Inserting a conductive rod 17 in the vicinity 'of each corner in the outer conductor '10 as defined'by the intersection of the inner conductors 12 and 13 and the slot 14 increases the radiation eificiency to approximately 50 percent. Additional rods 17 inserted along the opposite edges of the slot 14 as shown produce an increased efficiency approaching 65 percent. By connecting the wave guide 18 to the sandwich transmission line as described above, conventional modes of propagation within the guide are excited. In the embodiment shown herein in which a rectangular wave guide is utilized as an example,'the device becomes a mode transducer in which the TEM mode of sandwich line is transformed into, for example, TE mode in the ,guide '18. The enhanced radiation efficiency produced by the insertion of the conductive rods 17 clearly establishes the re-enforcement of the forward energy propagated by the slot with energy which tends to be radiated backwardly by the slot. This implies further that the backward radiating energy is reflected and radiated from the slot in phase with the forward propagating energy.

In the embodiment of Fig. 4 the tab 24 provides a means for varying the effective electrical length of the slot 14 for the dual purpose of tuning the slot to its resonant frequency and matching the impedance of the slot to the line. It will be apparent that where the device is utilized to translate energy from the sandwich transmission line to space, for example, as when used as an antenna, the impedance of the slot difiers from the condition where translation to wave guide transmission line is desired. Similarly, the resonance characteristics change and must be compensated.

It will be apparent from the foregoing described operation that the insertion of the conductive rods 17 greatly enhances the radiation efliciency of a resonant slot in sandwich line. The present invention greatly enhances the application of sandwich line to antennas and transmission lines, particularly wave guides.

While applicant does not intend to be limited to any particular dimensions in the embodiment of the invention just described, there follows a set of dimensions for the more important components which have been found to be particularly suitable at a frequency of 9,375 megacycles.

The slot, as shown in Fig. 1, is .900 inch long and .060

inch wide. The inner conductor is .165 inch wide and the outer conductors not less than .35 inch wide. The conductive rods 17 are .060 inch in diameter and spaced longitudinally and transversely .250 inch apart. The slot 14 and inner conductors 12 and 13 are centered relative to the four conductive rods in the vicinity of the intersection of the slot 14 and the inner conductors 12 and 13. The boundary defining surfaces on the guide are .900 inch apart and .400 inch long. The wave guide 18 as used herein silver plated and the conductors of the sandwich transmission line are .00135 inch thick and silver plated to approximately a depth of .0001 inch. The dielectric members 15 and 16 are .067 inch thick and formed from Teflon Fibreglas as manufactured by Continental Dimond Fiber Company.

While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore,

' aimed in the appended claims to cover all such changes ing: a pair of elongated, outer conductors providing ground planes; an elongated, inner conductor disposed in parallel with and in insulated spaced relation between said outer conductors; a resonant, elongated slot formed transversely in one of said outer conductors overlaying said inner conductor and intersecting an axis parallel with said inner conductor, said slot being electrically an integral number of half-wave lengths long and less than a halfwave length wide at the highest operating frequency of said device; and conductive means coupling said outer conductors in the vicinity of said intersection to enable increased coupling of high-frequency energy from between said inner and outer conductors through said slot.

2. A high-frequency wave translating device, comprising: a pair of elongated, outer conductors providing ground planes; an elongated inner conductor disposed in parallel with and in insulated spaced relation between said outer conductors; a resonant, elongated slot formed transversely in one of said outer conductors overlaying said inner conductor and intersecting an axis parallel with said inner conductor, said slot being an integral number of half-wave lengths long and less than a half-wave length wide at the highest-operating frequency-of said device; and a plurality of conductive rods connecting said outer conductors adjacent opposite sides of said slot with at least one of said rods in the vicinity of each corner in the outer conductor defined by the intersection of an axis parallel with said inner conductor and said slot to enable increased coupling of high-frequency energy from between said inner and outer conductors through said slot.

3. A high-frequency wave translating device, comprising: a pair of elongated, outer conductors providing ground planes; an, elongated inner conductor disposed in parallel with and in insulated spaced relation between said outer conductors; a resonant, elongated slot formed transversely in one of said outer conductors overlaying said inner conductor and intersecting an axis parallel with said inner conductor, said slot being an integral number of half-wave lengths long and less than a half-wave length wide at the highest operating frequency of said device; a conductor tab extending from said outer conductor into said slot'for tuning said slot and matching the impedance'of said slot to said line; and conductive means'coupling said outer conductors in the vicinity of said intersection to enable increased coupling of highfrequency energy from between said inner and outer conductors through said slot.

4. A high frequency wave translating device, comprising: a pair of elongated, outer conductors providing ground planes; an elongated inner conductor disposed in parallel with and in insulated spaced relation between said outer conductors; a resonant, elongated slot formed transversely in one of said outer conductors overlaying said inner conductor and intersecting an axis parallel with said inner conductor, said slot being an integral number of halfwave lengths long and less than a half-wave length wide at the highest operating frequency of said device; conductive means coupling said outer conductors'in the vicinity of said intersection; and a wave guide transmission between said inner and outer conductors through said slot.

5. A high-frequency wave'translating device, comprising: an elongated, planar, inner conductor; a pair of elongated, planar, "outer conductors providing ground planes and disposed in parallel with and in insulated spaced relation with respect to opposite sides of said inner conductor,'one of said outer conductors having an opening therethrough intersecting an axis parallel with and overlaying said inner conductor; and conductive means coupling said outer conductors in the vicinity of said intersection to enable increased coupling of high-frequency energy from betweensaid inner and outer conductors through said slot.'

References Cited in the tile of this patent UNITED STATES PATENTS Clappr. Nov. 6, 1951 Englemann Oct. 6, 1953 OTHE REFERENCES Electrical Communication, December 1953, pages 283-286. 

